1. Field of the Invention
The invention relates generally to sprayers and more particularly to aspiration-type sprayers for dispensing lawn and garden chemicals.
2. Description of Related Art
Aspiration-type sprayers are used to mix and dispense small quantities of a liquid based chemical into a relatively large carrier fluid such as water. The chemical may be liquid fertilizers or pesticides which are to be applied to crops, plants, lawns, flowers, vegetable gardens and other organic type vegetation. The chemicals are sold to the consumer in concentrated form and must be mixed in a proper proportion with a carrier fluid such as water before being applied to the crops etc. Such concentration chemicals may be hazardous to the consumer end user and environment in general. These chemicals are generally sold in plastic containers. Typically, an aspiration-type sprayer is coupled to the threaded neck of the plastic container and a water hose is coupled to the sprayer. The water hose shoots water through the sprayer which mixes with small quantities of the chemical drawn up from the container forming together a mixed stream. The mixed stream can be focused on the desired target to be chemically treated.
Several aspiration-type sprayers structures have evolved over the years. For example, U.S. Pat. No. 4,750,674 issued to Chow et al, discloses a sprayer having a system of air vent and aspiration openings of different sizes to obtain a selection of discrete mixing ratios. The mechanism requires a system of cups to block openings associated with nonselected aspiration rates and to provide the desired fluid communication. Such a system, however, requires the alignment and assembly of a plurality of elements including openings, cup seal and springs. Such a system is complicated to manufacture and assemble and therefore is undesirably expensive. Further, such devices fail to provide a simplified sprayer with a minimum of parts that are of simple design to promote reliability.
Other conventional sprayers, such as that described in U.S. Pat. No. 3,186,643 issued to George et al use a rotating carrier fluid valve having a range of adjustable carrier fluid flows in combination with a vent bore closure boss extending from the rotating valve. George et al's sprayer arrangement, however, like other conventional sprayers, disadvantageously has many parts which makes it an undesirable alternative for a low cost disposable type sprayer.
U.S. Pat. No. 2,837,374 to E. Lipman is not directed to a hose-end sprayer but to an atomizer cap for perfume bottles. While the Lipman patent illustrates the use of a slide plunger for connecting a liquid tube (extending within the perfume bottle) to an atomizing channel and a vent hole to atmosphere or for blocking both the liquid tube and vent hole it does not disclose any means for controlling the flow of pressurized carrier liquid such as water. Moreover, Lipman relies on O-rings for providing a seal between the slide plunger and a cooperating bore in the cap. The use of such O-rings in a low pressure environment adds to the manufacturing costs of the unit.
An improved aspiration-type sprayer is disclosed in U.S. Pat. No. 5,039,016 issued to Ronald Englhard and Donald Shanklin, the inventors of the present invention, which includes a sprayer head assembly sealingly mounted onto a container for storing a chemical to be dispensed. The sprayer head includes a multi-function unitary valve providing an aspiration opening simultaneously with full communication of the container interior to atmospheric pressure. The valve may include means for positive and simultaneous closure of the aspiration and vent passages so as to seal the chemical in the container when the sprayer is not in use. The sprayer assembly is coupled to a source of pressurized carrier fluid such as a garden hose. The carrier fluid is controlled by a control valve which blocks the flow of water from the hose when the sprayer is not in use.
Another improved aspiration-type sprayer is disclosed in U.S. Pat. No. 5,100,059 also issued to the inventors herein, Englhard et al, which discloses a sprayer having a unitary valve in the sprayer head assembly which controls carrier fluid flow from a pressurized source of water while simultaneously providing a controlled aspiration rate and full communication of the container interior to atmospheric pressure. The valve additionally includes simultaneous closure of the carrier fluid, aspiration and vent passageways so as to seal the chemical in the container when the sprayer is not being used. While the two afore-described aspiration-type sprayers provide many advantages over other sprayers, a simple arrangement that can be readily reproduced would be an advancement to the art.